Thread-controlling mechanism for sewing machines



July 17, 1934. E. B. ALLEN 'Er AL THREAD CONTROLLING MECHANISM FOR SEWING MACHINES Original Filed May 4, 1932 4 Sheets-Sheet 1 y N gmc/vm Edwddd. Allen -aMaurice l2 Knox July 17, 1934.

E. B. ALLEN Er AL 1,966,433

THREAD CONTROLLING MECHANISM FOR SEWING MACHINES Y 4 sheets-sheet 2 Original Filed May 4, 1932 3mm/tom Edward B. All en and Maurice l2 Knox Ju1y17,1934. E. B. ALLEN UAL 1,963,433

THREAD CONTROLLING MECHANISM FCR SEWING MACHNES Original Filed May 4, 1932 4 Sheets-Sheet 3 y 5 l fifi" Edward B. ./{lln and Ma urice 17. Knox 'Wwwe z July 17, 1934. vE Bl ALLEN Er AL 1,966,433

THREAD CONTROLLING MECHANISM FOR SEWING MACHINES Original Filed Ma'y 4, 1932 4 Sheets-Sheet 4 Wwmoaz Ma'uriceD. Knox Patented .uly 17, 1934 THREAD-CoN-'rnoLLI'NGy MECHNISM FOR ,A SEWING MACHINES Edward B. Allen and Maurice D. Knox, Newtown,

. J Conn., assigncrs to TheSinger Manufacturing Company, Elizabeth, N.QJ.",k a corporation ofv New Jersey omiginal yappliwtum May 4,'- 1932,'seria1 No 609,083.l Divided `and this application August '8,1933, Serial No. 684,142

supplyby the usual check-spring when thetension device is opened at the end of a sewing operation, Whereby the initial stitches of the kvnext sewingoperation maybe properly formedand set,

H'With,thezabove and other objects in view, as

. will hereinafter; appeanthe invention comprises the devices, combinations, and arrangements of partshereinafter set'forthjand illustrated inthe accompanying drawingsjof a preferredvembodi'- ment ofthe invention, from which the several :features of the invention andthe advantages attained thereby will `be readily .understood'by those skilled in the art.

IIn' the' accompanying elevation`of"a'buttonhole` sewing machine embody'iig' theinvention v` lig. 2 is a rear end eleva- 25Y tinof the machine. Fig'. 3 is a front end'elevation' of the machine.` Fig. 4 'is aview showing the action of the' check-spring blocking mechanisrn` associated With Athe tension release 'mechaniSmL` Fig. 5 is a top plan 'view 'of the upper work-clamp-foot, and Fig. 6 is' atop plan view of the'tension device and check-spring blocking means.

'Il'iefmachine chosenffor the purposes of the present disclosure'has a frame including the bed .35,

1, from which rises the hollow standard 2 of the gooseneck 3 terminating in the head 4. Journaled in the gooseneck 3 is the main-shaft 5 having at its front end the take-up operating crank 6 and the needle-bar reciprocating crank 7 which is connected by the link 8 to the needle-bar 9 carrying the needle 9 and journaled in the usual needle-bar gate 10 which is fulcrumedat 11 to perform Vibrating movements. The take-up crank 6 actuates the usual bell-crank take-up lever 12, Fig. 3, which is anchoredby the link 13 to the head 4.

The Work-clamp is of usual construction and comprises the upper rectangularly apertured clamp-foot 14 carried by the clamp-lever 15 fuli i crumed at 16 on the longitudinal slide frame 17 mounted in the cross-slide frame 18; the frames 17 and 18 being actuated through the usual connections with the feed-wheel 19 to shift the workclamp for the proper placing of the stitches to form the button hole.

drawings, Fig. 1 is a side The stop-motion device is preferably constructed substantially in accordance'with vthe disclosure of the YA llen'ancl Myers Patent No. 1,878,091; dated SeptemberZc, 1932; It'comprises the usual tilting stop-motion lever 20 fulcrumed at21 and carrying the upwardly spring-pressed stop-plunger'22 which cooperates'with 'the stop-can'1`23 connectedtofthe main-shaft 5. ",'Whenl the Inachine isrunning, the stop-motion lever 20 is tilted aboutits ,ful'criunl2l to carry. the upper endof the plunger 22, Fig. 1, Ito'fthe right and 'out of rangeof the 'stop-cam 23. ,When the stop-inotion lever 20 isreleased to stop the macliine,y it returns to its vertical position', Fig'. l,l and carries the spring-pressed stop-plunger 22v into the path of the-stop-cam v,23 which iir'st depresses'the plunger22 and finally 'permits thepIunger to rise intor a stop notch 23'l vinthe cam` and stop the machine ata Ypredetermined point with the needle 9f'outfof the'work and the'take-up 12at its highest point.v v

'The stop plunger 22 carries the usual laterally extending vblock 24 which engagesr under 'the spring-pressedfplunger 25 in the arm 26 "of the usual stop-motion-controlled rock-shaft 27 uand gives Asuch rock-'shaftan impulse astheplunger `2'vrises .to :iinal stopping positionfvinthe notched stop-'camM-ZS.' This impulse given to' th'e rockslaft 27 is'utiliaed for various purposes in a machine vof `the presenttype, notably forreleasing the tension device 28, as will be hereinafter Ydescribed. l f l The needle 9 y cooperateswith .the rotaryhook mechanism 29 to', form. stitches, as f fdisclos e d in our saidcopending application.

The needle-thread t runs from the supply through the top tension-device 30, thence around the thread-guide 31 and through the side tensiondevice 28; thence past the guide 32 and through the check-spring 33 and under the guide34 to the take-up 12 and down to the needle 9.

At the end of a sewing operation the upper tension-device is opened by the Wedge-bar 35, Fig. 1, connected to the lever 36 Vwhich is connected by a link 37 to the tilting stop-motion 100 lever 20. The side tension 28 is opened by the wedge-ended curved arm 38 carried by the rockshaft 39 journaled in the head 4 and having fixed to it a rearwardly extending arm 40 carrying a ball 40' engaging the forked end 41' of an arm 41 fixed to the stop-motion controlled rock-shaft 27, Fig. 3. The side tension 28 applies a uniform tension to the needle-thread at all times when the machine is sewing. The check-spring 33 performs its usual function of taking up the slack thread between the eye of the descending needle 9 and the work. The upper tension-device 30 is automatically controlled to apply various additional amounts of tension to the needle-thread to meet the requirements of sewing the rst side, the return side and the barring stitches at the ends or" the buttonhole. The mechanism for 0perating the upper tension-device during the sewing will not be described herein as it forms no part of the present invention.

At the end of a sewing operation the needlethread t is cut and nipped by the usual needlethread cutter1 and nipper 42Figs. 4 and 5, carried by the clamp-foot l14 and actuated by the springretracted rod 43 which is released by the upward movement of the arm 44 when the operator pulls down on the lever 45 to open the work-clamp. This mechanism is constructed substantially in accordance with the disclosure of the clampopening and needle-thread-cutter-tripping mechanism in the Allen application Serial No. 551,114; filed July 16, 1931.

The present machine is designed more particularlyto sew a pyramid purl stitch which is accomplished by the cooperation of an upper eyepointed zigzag or laterally vibrating needle with an under thread-mass or bobbin associated with a loop-taker which seizes thread-loops from the needle below the work and expands such loops ior passage about the under thread-mass or bobbin. The needle-thread take-up is required not only to draw up the needle-thread loops after they have been interlocked with the bobbinthread, but also to draw such loops entirely through the work, pulling loops of bobbin-thread through to the upper side of the work, so that in the nished seam the needle-thread will lie in substantially a straight center line between the rows of zigzag needle-punctures, while loops of bobbin-thread emerge from the needle-punctures at the upper side of the Work and embrace the straight needle-thread. In the formation of such a pyramid-purl seam along the sides of a buttonhole, about tWenty-thousandths of an inch of needle-thread is used per stitch while about three-sixteenths of an inch of bobbin-thread must be supplied from the bobbin and pulled upwardly through the work by the take-up in drawing up the needle-thread loop. The tension on the bobbin-thread must necessarily be light while the tension on the needle-thread must be very strong.

It will be evident that when the machine is sewing, every time the take-up moves to its highest point the strain on the needle-thread overcomes the weak tension of the check-spring and pulls it over to the strained position shown in full lines in Fig. 4. At the end of a sewing operation the tension-devices are automatically opened and the check-springhas a tendency to recover its initial or dotted line position, Fig. 4, and steal needle-thread through the open tension-devices. If this action were permitted to occur at the end of a sewing operation with the needle-thread end held in the nipper in the clamp-foot, the machine would have to make several stitches in the next buttonhole producing cycle to use up the slack needle-thread stolen from the supply by the check-spring. During the sewing o1" these several stitches the bobbinthread loops would not be properly pulled to the upper side of the work and defective stitching would result. 'I'o overcome this diiculty there has been secured to the tension-opening arm 38 a check-spring blocking arm 46 having a V-throat 47, Fig. 6, in its free end adapted to hold the check-spring in its fully strained position, Fig. 4, to prevent such spring from recovering, when the tension-devices are opened and 'stealing thread from the supply.

Having thus set forth the nature of the invention, what we claim herein is:-

l. In a sewing machine, in combination, stitch forming mechanism including a reciprocating needle, a loop-taker, a take-up, a tension-device, a check-spring, a needle-thread cutter and nipper, a stop-motion device for the stitch-forming mechanism arranged to stop the latter with the take-up at the end of its stitch-setting action and the check-spring under the strain of the needle-thread, means for opening the tensiondevice, and means for holding the check-spring in its strained position while the tension-device is open. j

2. In a buttonhole sewing machine, in combination, a reciprocating needle, a loop-taker, a

work-clamp, a stop-motion device, a take-up, a tension-device, a check-spring associated with said tension-device, tension-release mechanism connected to be operated by said stop-motion device; a needle-thread cutter and nipper on said work-clamp, and means connected with said said tension-release mechanism for blocking the recovery motion of the check-spring to prevent the check-spring from stealing thread from the supply through the released tensiondevice.

EDWARD B. ALLEN. MAURICE D. KNOX. 

